Anchor rods embedded in concrete foundations are the structural interface between the building frame and its foundation — transferring column base shear, tension, and moment to the concrete. The welded connection between ASTM F1554 anchor rods and their embed plates or template washers is a structural weld that many shops treat as routine fabrication, but it carries real code obligations under AWS D1.1:2025 and IBC Chapter 17 special inspection requirements.
This article covers what CWIs and fab shop QC managers need to know: which F1554 grades are prequalified, when a PQR is required, how to select filler metal and preheat for each grade, and what the IBC special inspection record must contain.
F1554 Grade Overview and Weldability
ASTM F1554 covers anchor bolts and rods in three yield strength grades:
| Grade | Fy min (ksi) | Fu min (ksi) | AWS D1.1 Status |
|---|---|---|---|
| 36 | 36 | 58–80 | Prequalified |
| 55 | 55 | 75–95 | Prequalified |
| 105 | 105 | 125–150 | Not prequalified — PQR required |
The weldability difference between the grades is significant. Grade 36 behaves like A36 plate — forgiving chemistry, low CE, minimal preheat needed for most rod diameters. Grade 55 has a controlled chemistry that keeps CE in check despite higher strength. Grade 105 is a quenched and tempered (Q&T) product; its CE typically runs 0.60 or higher, and the heat-affected zone is sensitive to hydrogen-assisted cold cracking.
Rule: Always calculate CE from the MTR for the specific heat of F1554 rod being welded. Do not assume the grade chemistry matches a prior order from the same supplier.
Prequalified WPS for F1554 Grade 36 and Grade 55
For Grade 36 and Grade 55, a prequalified WPS under AWS D1.1:2025 Clause 5 is the standard path. The WPS must document:
Joint design. Anchor rod-to-plate connections are typically:
- Fillet weld around the perimeter of the rod where it passes through a template plate (plug-type or perimeter fillet)
- Bevel groove weld at the rod-to-base plate connection when full-penetration strength transfer is required by design
- Double-fillet weld at a rod-to-washer plate sandwich configuration
Prequalified joint geometries from AWS D1.1:2025 Annex B apply. Fillet weld sizes must meet minimum size requirements based on the thicker part joined — typically the embed plate or base plate thickness, not the rod diameter.
Filler metal. E7018 (SMAW) for Grade 36 rods. For Grade 55 rods, the higher-strength base metal warrants E7018 or E8018 to ensure adequate tensile compatibility. Low-hydrogen electrodes (H8 or better) are required for Grade 55 in diameters above 1-1/4 inch due to the restraint of the round rod geometry and the heat sink of the connected plate.
Preheat. Grade 36 rods in typical diameters (3/4 to 1-1/4 in) with CE below 0.45%: minimum 50°F preheat. Grade 55 rods with CE in the 0.45–0.55% range: 150–200°F preheat. Verify with contact pyrometer at the rod and the plate, measured 3 inches from the weld.
Position. Embed plate welding typically occurs in the flat (1F/1G) position in the shop. Field installation of additional weld passes at erection (rare but occurs on heavy industrial jobs) may require vertical (3F) or overhead (4F) qualification on the WPS.
Tested WPS for F1554 Grade 105
Grade 105 is not in the prequalified base metal list. Any WPS for welding Grade 105 anchor rods requires qualification by test under AWS D1.1:2025 Clause 6, documented on a PQR.
The essential variables that govern qualification under Table 6.6 include:
- Base metal group change: qualification on Grade 105 does not qualify Grade 36 or Grade 55 (different base metal groups)
- Filler metal classification: changing from E9018 to E10018 is an essential variable change requiring requalification
- Preheat decrease: lowering preheat below the PQR-tested minimum is a requalification trigger
- Position: welding in a position not covered by the PQR position qualification range requires requalification
For the PQR test coupon, the test plate or pipe must represent the production joint geometry. A fillet weld macro test (macro etch examination) on a fillet weld PQR specimen demonstrates fusion, throat, and HAZ characteristics for Grade 105. Macro etch reveals the quenched and tempered microstructure and confirms there is no HAZ cracking or softening anomalies.
Controlled heat input is mandatory for Grade 105. Excessive heat input destroys the Q&T microstructure in the HAZ, reducing hardness and strength. The WPS should specify a maximum heat input (kJ/in) based on the qualified range — this is an essential variable change if exceeded in production.